1. Field of the Invention
The present invention relates generally to an electrode material to be assembled into a-vacuum interrupter. Specifically, the present invention relates to such material composed of silver (Ag) and chromium (Cr) with low contact resistance and excellent breaking ability.
2. Description of the Background Art
Conventionally, copper(Cu)-bismuth(Bi) alloy is utilized for an electrode material of a vacuum interrupter. Such electrode material made of Cu-Bi generally contains less than 1 wt. % of Bi against the amount of Cu, which is a basis metal, to increase welding proof of the material. Cu-Bi alloy has low contact resistance appropriate for electrodes which can provide large current. However, the material has certain problem in voltage resistance and breaking ability thereof.
Copper(Cu)-chromium(Cr) alloy in which Cr particles dispersing in a Cu matrix is also utilized for the material for the aforementioned usage because of superior voltage resistance and breaking ability thereof to Cu-Bi alloy. However, contact resistance of the alloy is relatively higher than that of Cu-Bi alloy, specifically, contact resistance significantly increases when current is broken.
In addition, electrode materials containing silver(Ag) is also known in the art, however, breaking ability thereof is inferior to that of Cu-Cr alloy or Cu-Bi alloy. Therefore, application of Ag containing material is limited as Ag-WC alloy for switches which are not frequently suffered from current breaking.
Recently, according to improvement of the vacuum interrupter, electrode materials with low contact resistance having superior voltage resistance and breaking ability to those of materials made of Cu-Bi alloy are more and more required for the electrode which can provide large amount of current.